This essay offers a historical traveler’s report on a strange imaginary land, one that had few of the distinctive marks by which we usually identify a state. It did have a distinctive name: Respublica literarum, the Republic of Letters. Its citizens agreed that they owed it loyalty, and almost all of them spoke its two languages—Latin, which remained the language of all scholars from 1500 to 1650 or so, and still played a prominent role thereafter, and French, which gradually replaced it in most periodicals and almost all salons. But it had no borders, no government, no capital. In a world of sharp and well-defined social hierarchies—a world in which men and women wore formal costumes that graphically revealed their rank and occupation—its citizens insisted that all of them were equal, and that any special fame that one of them might enjoy had been earned by his or her own efforts. As one observer put it in 1699, “The Republic of Letters is of very ancient origin . . . It embraces the whole world and is composed of all nationalities, all social classes, all ages and both sexes . . . All languages, ancient as well as modern, are spoken. The arts are joined to letters, and artisans also have their place in it . . . Praise and honor are awarded by popular acclaim.”[1] The Republic of Letters imagined itself as Europe’s first egalitarian society, even if it did not always enact these high ideals in the grubby reality of its intellectual and professional practices.

The citizens of the Republic were the last Europeans who could plausibly claim that they were masters of their entire civilization. We live in a world of specialists. From engineering and mathematics to philosophy and criticism, success means something specific: defining a problem precisely and solving it in a formal, definitive way. Only other specialists, we believe, can or should tell us if such problems have been solved. We find ourselves baffled and worried when, as has recently happened in the super-specialized realms of mathematics and physics, the specialists don’t seem to agree about who proved the Poincaré conjecture or whether string theory will ever reveal something about the real world.

Specialists and professionals are, for the most part, recent creations: the denizens of modernity, a world in which every highly educated man or woman has a particular function, and has obtained a formal license to practice it.[2] In pre-modern Europe, specialists existed: but even those who proudly described themselves as “mathematicians” or “critics” practiced their arts in a broad context. For the whole system of formal education was geared to produce generalists. Every learned person became a classicist at school. Specialists in the ancient higher faculties—medicine, law, and theology—imported their humanistic training into these fields, and changed the humanities by bringing medical, legal and theological perspectives to bear on them.[3] And specialists in a more modern sense often did the same. Even the most gifted mathematicians studied Greek and Latin and history at school and logic and philosophy at college, before they turned to numbers. Nowadays we remember Leibniz and Newton as scientists, the great men who created the calculus and modern physics, and Leibniz as a philosopher as well. Though the two men took justified pride in their extraordinary achievements in what now seem these central fields, they also pursued their interests into many neighboring ones. Leibniz was a productive, critical historian and a penetrating student of the origin and development of human languages. Newton spent years of his life performing alchemical experiments, reworking the history of the ancient world, reconstructing the Temple of Solomon and trying to interpret the prophecies of Daniel and the Book of Revelation. Thousands of pages of tightly written notes record his efforts in these multiple fields—each of which he apparently took as seriously as the rest. Both men wrote Latin as easily as the modern languages, and often chose to use it—or, in Leibniz’s case, French—when addressing issues of importance to a wide audience.

One way to imagine the Republic, then, is as a sort of Pedantic Park: a world of wonders, many of them man-made, inhabited by scholarly dinosaurs. The Republicans haunted the massive, classical libraries that patrons preferred where busts of the heroes of letters stared down from the laden shelves; stared politely at the rhinoceros horns, skis and Etruscan weapons artfully heaped on the walls and shelves of cabinets of curiosity, and savored the circular spectacle of the anatomy theater—at least in the winter, when the corpses didn’t stink.[4] Each of these preferred habitats reflected their eclectic tastes: every one was an encyclopedia—designed to teach lessons, some of them material or visual, about man and nature, science and history—and a laboratory, in which new forms of knowledge took shape. Leiden University’s celebrated anatomy theater, for example, bristled with human and animal skeletons, neatly arrayed to teach comparative anatomy. Men and horses—or at least their articulated bones—held up banners with Latin devices, designed to impress on visitors the moral lessons of mortality as well as the technical ones of zoology. Skeletal figures of Adam and Eve drove home the theological moral. The university’s equally celebrated library offered visitors books and manuscripts, city views, globes, and atlases—and learned conversation, during its few weekly hours of opening.[5]

The dinosaurs themselves came in many forms. Most of them were mild plant-eaters. But the gentle savants were flanked by vast lumbering monsters of erudition, like Athanasius Kircher, who lived a life of adventure, physical and intellectual, that Indiana Jones might have envied. Kircher climbed into the crater of Vesuvius in pursuit of an understanding of volcanoes, helped Bernini design the Fountain of the Four Rivers, amused himself working out the magic tricks of the conjurers who performed next to the Fountain in the Piazza Navona, played football against the Dominicans—and speculated, in ways that frightened and angered the religious authorities, about heliocentric astronomy and the pre-diluvial history of Egypt and China. He preserved his complex thoughts on all of these subjects in a vast array of massive, heavily illustrated Latin folios—more than any modern scholar could possibly read, much less write. While his books reportedly found few buyers, they won generous support from patrons and widespread interest—as well as considerable ridicule—from readers.[6]

The Republicans of Letters were not uniformly distinguished for integrity and generosity. Noel Malcolm has compellingly argued that Kircher’s pursuit of secrecy—not to mention his unfounded claims to mysterious knowledge about ancient Egypt and much else—put him in conflict with the Republic’s principles of openness, transparency, and full citation of evidence. But Kircher’s aggressive pursuit of knowledge, patronage and fame was not unusual in this world. Under the feet of the giants, swift, vicious little raptors fought and tore their way to prominence with equal energy: for example, Justus Lipsius, the brilliant textual critic who offered to recite the text of Tacitus, with a knife held to his throat, to be plunged in if he made a mistake. Lipsius’s moral writings made him the widely respected prophet of high Stoicism, the preferred moral code for scholars in an age of absolutism and religious war. In recent decades, scholars have emphasized his sophisticated pursuit of the lessons of Tacitus and Polybius and his ability to codify the results of sixteenth-century antiquarianism for a new readership, which he reconfigured so successfully that they proved indispensable for the practical purposes of military reform. Some have assumed that Lipsius—and his Stoical philosophy—can stand as a kind of moral counter for the early Republic of Letters as a whole. But he ensured his reputation as a textual critic by snitching other scholars’ clever emendations, which he recorded in a working copy of Tacitus now held in Leiden. Sadly, his efforts to erase the evidence did not succeed.[7]

Yet Kircher and Lipsius, for all their idiosyncrasies, offer what seem still to be powerful models for the conduct of intellectuals. They devised ways to conduct research with rigor, even when its results were uncomfortable; to publicize their results, without fear or favor; and, again and again, to rise above their prejudices without losing their convictions—as both men did when they maintained friendships that spanned ideological and political borders. And they also both collaborated, to spectacular effect, with artists, who gave their books a radically new visual form and, in Kircher’s case, realized his vision of ancient Egypt in the piazzas of modern Rome. They still, I now believe, have much to teach us about the forgotten premodern intellectual worlds that they inhabited and explored, and also, perhaps, about how modern intellectuals could and should serve the public good in our own poisoned public sphere.

We must remember, first of all, that the period in which the Republic of Letters flourished most was no golden age for Old Europe. The phrase Respublica literarum appeared in the fifteenth century, as a euphonious way to describe “the literary enterprise” or “the cause of letters.” The Republic itself, however, really began to take shape in the consciousness of scholars around 1500, as Erasmus became the leader of a self-conscious avant garde of scholars bent on reforming the Church and the universities.[8] And this process unrolled only a few years before Martin Luther and his Reformation split the Catholic church, which had been unified for more than a thousand years, forever.

The Republic barely survived the years from 1550 onwards, when militant Catholics and Calvinists in France and the Low Countries created what amounted to the first national revolutionary parties, organized by cells and inspired by absolutist ideologies, and fought civil wars of terrifying brutality. These years were marked by such terrible events as the Massacre of Saint Bartholomew and the assassinations of Kings Henry III and IV of France and William of Orange—assassinations made easier, as Lisa Jardine has shown, by the rise of the handgun, a curse then as now.[9] Yet the Republic staggered onwards, and even flourished, during the first half of the seventeenth century, even as almost all the European powers found themselves drawn into the Thirty Years’ War that turned Germany, then known as the Holy Roman Empire, into an impoverished and backwards set of principalities.

All this is to say nothing of such horrors as the witch trials of the same period, that deprived thousands, most of them women, of life itself on the grounds that they had had intercourse with devils, called up storms to destroy crops, and stolen men’s penises, which they hid in birds’ nests; or of the imposition of censorship in much of the Catholic world; or of the systematic oppression of Jews. It was a harsh world, as one might expect, since the men who ruled it generally cherished absolute convictions about life, the universe, and everything. As Brad Gregory has recently shown in a stunning book, hundreds of men and women died for their religious beliefs, willingly and bravely, after the Reformation began. Not a single one of the officers who imposed these punishments and watched them carried out, whether Catholic or Protestant, Lutheran or Calvinist, seems to have felt any qualms about inflicting martyrdom—to say nothing of converting to the martyrs’ faith, or to have repented after watching the martyrs suffer.[10]

Yet across this ocean of darkness—so historians have been learning over the last half-century and more—small bands navigated in fragile craft: little communities of scholars, whose members did their best to maintain a different kind of society, with its own rules and its own values. Many of the Republicans of Letters held official positions in universities, courts, or academies, and some used their skills to express imperial and national visions.[11] Others managed to hold official positions and still work for the Republic’s own vague but vital ideals of peace and tolerance.[12] But some were barred from most such posts by their conviction that they could not serve the state or the institutional church without being swallowed up by it and forced to violate the teachings of their consciences.

Whether the Republicans belong to an establishment or were hunted by one, they lived lives characterized by movement and distance. Protestants and Catholics alike crossed nations, borders, sometimes whole worlds. The distinguished older literature on the Republic of Letters—the books and articles of Annie Barnes, Erich Haase, Paul Dibon—concentrated on the Huguenot Refuge. They treated it, as Hugh Trevor-Roper summed up in a brilliant, over-generalized article, as the refuge not only of Protestant intellectuals and artisans, but also of an Erasmian ideal of tolerance.[13] More recently, students of the Catholic world have placed the Jesuits, always in purposeful motion, on the same imaginary map, and shown that they and the Huguenots—even as they denounced one another—cultivated the same fields of study, from natural science to the art of reading history, and sometimes even pursued the same ideals of civility and collaboration. The network of correspondents that linked a José de Acosta, writing on the natural and moral history of the New World in Peru, to fellow Jesuits from Rome to China—and the knowledge transmission belts that, as Paula Findlen has shown, brought the results of Kircher’s Egyptology from Rome to the cloister of Sor Juana in New Spain—were as global as those that brought the Samaritans in Palestine and the Jacobite Patriarch Ignatius Na’amatallah in Rome into productive contact with the Huguenot Joseph Scaliger in Leiden.[14] The Republic of Letters existed, first and foremost, as a palimpsest of people, books, and objects in motion.

Motion, of course, was always difficult and sometimes dangerous in the premodern world. But it also had much to offer. Travel—as we have learned from Justin Stagl, Joan-Pau Rubiés, and Paola Molino—became an art in the sixteenth and seventeenth centuries.[15] The Republicans of Letters drew up for each city they visited a questionnaire with spaces for geographical setting and urban form, natural resources and crafts, literary and religious life. They used this as a hermeneutic, which enabled them to read urban spaces as if they were texts (just as the antiquaries knew how to read texts so as to set them back into the three-dimensional cities where they had originally been produced). As they traveled, they learned about the diverse characters of nations. But at the same time, they followed the thinnest capillaries of the Republic of Letters, seeking out their fellow Republicans in their local habitats. In city after city they performed the homosocial rituals of their kind, offering the respects of friends elsewhere and entering signatures, epigrams and rebuses into one-another’s alba amicorum.[16] By doing so, they made deposits in a bank of social and cultural capital that would serve them throughout their lives.

Distance and motion had other functions as well. Above all, distance lent prestige—especially to such apparently glittering centers of new intellectual life as Louvain in the early sixteenth century, Leiden and Prague a century later, and Amsterdam and London later still—not to mention Paris and Rome, the eternal beacons of erudition and antiquity. By contacting a dominant figure in one of these glittering galaxies of talent and receiving a testimonial of warm approval, one could win credit in one’s own local, competitive environment. That is why, as Mario Biagioli has recently taught us, Galileo set such store by Johannes Kepler’s approval of the findings that he announced in the Sidereal Messenger. The mathematician beleaguered by local critics and competitors in northern and central Italy was bathed in a glowing nimbus of support by the detailed letter sent by the Imperial Mathematician from far-off Prague.[17]

The stars that glittered most brightly across distance were usually cities. The Republicans often had to spend time and provide services at courts. But they liked cities that enjoyed a certain measure of autonomy, and whose governors did not share the general belief that torture and execution were the appropriate tools for reducing religious and intellectual dissidents to order and submission. The citizens of the Republic also needed to perch near certain urban institutions: libraries, for example, and the printing presses that gave men and women of letters their only power, that of publicity. Their favored places, the capitals of their imagined state, included Strasbourg, a border town, cosmopolitan and tolerant; Leiden and Amsterdam, the Dutch trading centers, in which Catholics and Calvinists, Anabaptists and Jews rubbed elbows in mutual tolerance—and all of them joined to reject what they called “the Genevan Inquisition,” when doctrinaire preachers tried to carry out an ideological cleansing; and, of course, Basel, where Erasmus and other irenic souls found a spiritual home—a city ever hospitable to refugees from oppression in their native countries. London and Berlin also figured on the imaginary maps of the Republic, since both cities harbored many of the refugee French Protestants who made up a major share of the republic’s population.

Cities, after all, offered unique intellectual resources. In such forcing-houses of talent and research as the Lime Street community in Elizabethan London, reconstructed with great skill by Deborah Harkness in The Jewel House, clusters of artisans and apothecaries, Paracelsians and natural historians made their shops and gardens into a vast collective laboratory—something like an embodiment of Bacon’s supposedly Utopian New Atlantis, in which intellectual workers of very different kinds coordinated their efforts to force nature to reveal her secrets. Yet this local world had foreign as well as British inhabitants and was closely connected, by contacts made in travel and correspondence networks that passed through the Low Countries to the rest of Europe, with a vast range of impressive foreign contacts, who appreciated its lively, fertile culture.[18] The active, engaged, and sometimes quarrelsome form of collaboration between artisans and scholars that Harkness has turned up in London had become a standard feature of cultural life in Renaissance Italy, and would characterize the Republic throughout its history.

Cities also were the habitats of most of the learned women—beneficiaries, as Sarah Ross and April Shelford have taught us, of surprisingly ardent support from the Latin-speaking patriarchy—who created such salons as that of the Dames des Roches in Poitiers, and who, in the later seventeenth and eighteenth centuries, entered such once male preserves as the realm of classical philology.[19] Yet country houses, with their alluring Mannerist gardens, also offered islands of civility, many of them superbly stocked with books and antiquities, and historians of the Republic of Letters in the German and Austrian lands have emphasized the role of these aristocratic enclaves.[20]

Wherever they found jobs or refuge, the Republicans continued to respond to changes in the world outside the scholarly enclaves. Gradually they ditched backward-looking Latin for the up-to-date language of civilization, French, and took their campaigns against persecution and oppression to a wider public, even as the wars of Louis XIV turned much of northern Europe into a wasteland, and systematic oppression and abuse almost destroyed France’s own Protestant communities.[21]

The citizens of the Republic carried no passports, but they could recognize one another by certain marks. Not wealth, of course; then as now, scholar did not rhyme with dollar. But they looked for learning, for humanity, for generosity, and they rewarded those who possessed these qualities. Any young man, and more than a few young women, could pay the price of admission. Just master Latin—and, ideally, Greek, Hebrew, and Arabic; become proficient at what now seem the unconnected skills of mathematics and astronomy, history and geography, physics and music; turn up at the door of any recognized scholar from John Locke in London to Giambattista Vico in Naples, bearing a letter from a senior scholar, and greet your host in acceptable Latin or French—and you were assured of everything a learned man or woman could want: a warm and civilized welcome, a cup of chocolate (or, later, coffee); and an hour or two of ceremonious conversation on the latest editions of the classics and the most recent sightings of the rings of Saturn.[22]

If this state had no maps, no administrative officials, and no borders, how do we know it existed at all? And how can we define it more precisely? We know the Republic, in the first instance, from what its citizens tell us about it. The documents in which they discussed it form the primary archive from which we can draw both descriptions and evaluation. Not all contacts were informal. Traditional historiography has emphasized the scientific societies that took shape over the course of the seventeenth century, and whose officers and members did their best to establish new criteria and methods for the proper study of nature: the Accademia del Cimento, the Lincei, the Académie des Sciences and the Academia Naturae Curiosorum.[23] More recent studies have taught us to see these as one particularly vital species within a larger genre. The Republicans of Letters created many local communities of savants, dedicated to the search for religious or secular truths, or both at once. In some cases, as in the sixteenth-century Neapolitan academies that dedicated themselves to hunting out the secrets of nature or the seventeenth-century utopian brotherhoods that took shape in Tübingen or elsewhere, individuals or groups drew up formal rules for membership and elaborate protocols for the proper pursuit of intellectual life.[24] In others, like the Cabinet of the brothers Dupuy or Théophraste Renaudot’s Bureau d’Addresse, membership and activities formed more spontaneously.[25] In any number of cases, only a textual record remains, raising questions that remain difficult to resolve about whether a given society functioned in the material and social world.[26] Nonetheless, these organizations clearly played vital roles. They made clear that intellectual life needed a social foundation—and needed it all the more as Europe’s age of religious war progressed. And they helped to create the epistolary networks that gave the Republic its true circulatory system.

It is above all in the thousands of surviving letters—letters that combined the official and professional with the personal in a way that in the pre-modern world seemed entirely natural—that the outlines, highways and capitals of the Republic can be glimpsed most vividly. Tucked into letters were the reports on barometric experiments and the movements of falling bodies, the specimens of Egyptian mummy and New World flora, the drawings of rhinoceros horn and Roman feet, the descriptions of newly discovered manuscripts of ancient texts, the historical and political information that enabled men and women to know what was happening in the great world outside their little town, and to compile the great syntheses of political, historical, philosophical and scientific information that we still read: the work of Grotius on natural law, Galileo on natural philosophy, Locke on the nature of property. To a world that has largely abandoned letters except when asking for money in a good cause, these epistles—with their formal Latin salutations and intimate details of urinalysis and kidney stones, astrological predictions and monstrous births—may seem quaint. In their day, however, they constituted the fragile but vital canals that connected and animated intellectual commerce in the far-flung parts of the republic. The strands of long-term correspondence formed a capillary system along which information could travel from papal Rome to Calvinist strongholds in the north, and vice versa—so long as both had inhabitants, as they did, who wished to communicate.[27]

The constant writing and sending of letters was more than a system for collecting and exchanging information. The citizens of the Republic saw it as a moral duty: at once the only way to show their sympathy and affection for those from whom political and religious borders separated them and the only way to enter into a regular relationship with the greats who glittered far away. Consider just one instance: Erasmus, the great teacher and letter-writer, whose textbooks dominated the schools and universities of northern Europe until the middle of the seventeenth century, and whose own correspondence fills twelve volumes in the great modern edition published by the Clarendon Press. Erasmus treated the letter as a literary genre in its own right, and set down rules for the composition of effective, eloquent letters. In one of his textbooks—the aptly named On Copiousness in Words and Ideas—he went further, listing hundreds of ways to say “As long as I live, I shall remember you” and “Thank you for the letter” in elegant, correct Latin. The effort seems disproportionate to the task, until we realize that, as Kathy Eden has made clear, Erasmus deeply believed both in the community of intellectual and literary property (“all the property of friends is held in common,” he liked to say, quoting the ancient Greek thinker Pythagoras) and in the connection between the language one used and the state of one’s mind and soul.

The scholar, for Erasmus, must school himself or herself to write, over and over again, to critics as well as supporters, enemies as well as friends, professing friendship and concern. By doing so, one would knit up the raveled sleeves of particular relationships. But one would also become a true friend, one genuinely devoted to and concerned for others. The vast series of letters that fill dozens of volumes in every great European library are the relics of a great effort, inspired by Erasmus and many others after him, to create a new kind of virtual community: one sustained not by immediate, direct contact and conversation so much as by a decades-long effort of writing and rewriting.[28]

These exchanges, as Anne Goldgar and Brian Ogilvie have taught us, followed, or were supposed to follow, a strict code. Write to another scholar and you engaged yourself to reply to future letters in reasonable time, to give credit to your correspondent for information received and suggestions accepted, and to call him or her a friend—a term that had a strong formal meaning.[29] Yet for all the coded formality of their Latin and French, for all their authors’ desperate efforts to create personae on paper, and for all the breaches of epistolary etiquette that fused the circuits of this vast mechanism of exchange, many of them remain very moving.[30]

As this example suggests, some of the Republic’s qualities give it a genuine contemporary relevance. Like us, its citizens made conscious efforts to create communities, both of people and of information, that crossed political, linguistic and religious borders. Like us, they did their best to manage the vast amount of information to which they had access. The early modern period, as Ann Blair, Richard Yeo, Daniel Rosenberg and Noel Malcolm have shown, witnessed multiple efforts to capture, organize and make available to all the vast amounts of information flooding into Europe from travelers, compiled by scientific observers, and excavated by historians—a flood not only reproduced, but magnified, by the printing press. The tools they forged included not only scholarly correspondence of a personal sort, but also both technical and literary models for stockpiling information and making it available: the bibliography, the filing cabinet, the compilation of “historia litteraria” and the journal.[31] From the 1660s onwards, a swarm of new printed publications, in both Latin and the modern languages, compiled new information, reviewed new books, and made it possible, for the first time, for intellectuals across Europe to have reliable, regular information on the doings of scholars—and kings—in every other corner of the European world.[32]

Trade had become global again in the fifteenth century. Now information also joined the global flow, as Huguenots in exile in Berlin and Potsdam informed the European world about recent science and scholarship in French. Kircher, admired and envied in Rome, drew information from fellow Jesuits around the world as he charted the underground movements of rivers and lava flows and the ancient migrations of peoples. Vico, isolated but well-informed in Catholic, southern Naples, used Dutch journals published in Latin as his primary sources for the new theories of Spinoza and Locke. Like the blogs that have accelerated the movement of facts and ideas in recent years, the new journals and publishing houses had a profoundly unsettling effect on political and social authorities. The Republic of Letters stood, in the first instance, for a kind of intellectual market—one in which values depended, in theory at least, not on a writer’s rank but on the quality of his or her work.

The Republic, moreover, was more than a sprawling series of social and intellectual networks, loosely linked by curiosity about nature and history. It would be wrong to suggest that it had a single ideology or an official set of beliefs—even that of the Radical Enlightenment recently reconstructed with such brio by Jonathan Israel.[33] Its citizens, after all, included Catholics of different sorts, Protestants of every flavor, a few Sephardic and an even smaller number of Ashkenazi Jews—in addition, as time went on, to Unitarians and others who abandoned all the established churches. Patriotic Dutch scholars presumably felt a shiver a pride—and patriotic British ones just a shiver—when a Dutch fleet sailed up the Medway and burned much of the English navy.

Moreover, and more important, many of the most erudite scholars, Catholic, Calvinist, and Lutheran, pursued their research largely, or even primarily, for partisan reasons: in order to ensure the triumph of a religion—or, in other cases, a ruling house. Jesuits in China and elsewhere showed a deep interest in alien systems of belief and practice: yet their primary goal was the conversion of the world to Catholicism, and even a Matteo Ricci found it easy to draw the line between Chinese beliefs that he saw as compatible with Christianity and those that were not.[34] The large-scale research enterprises mentioned in my recent book—the teams of scholars assembled to study the history of the Church—found patrons because they promised to supply weapons to be used in confessional strife.[35] Even those who consciously tried to see the merits in others’ programs and practices were still driven, much of the time, by theological convictions. Isaac Casaubon’s demonstration that the philosophical Hermetica were late rested on his mastery of the language and technical philology. But it was motivated by an absolute conviction that neither Cardinal Baronio, whose work he dissected at enormous length, nor a pagan like Hermes who supposedly anticipated Christian truths, could possibly have written in good faith.[36]

And yet certain views, shared in greater and lesser degree by the Republicans, ran counter to the confessionalism of the time. Some of them, for a start, believed that it was simply wrong—morally wrong and intellectually wrong—to break off communications with those who didn’t share their religious beliefs or their political views. Knowledge and sociability, after all, mattered most: and restrictions could only hamper the flow of information and ideas. That helps to explain why a long series of Vatican librarians, in the heart of papal Rome, admitted Protestant scholars as freely as Catholic ones.

A fair number went further. In an age of brutal persecution, when torture was the standard legal method on the Continent for extracting information and confessions, scholarly citizens of the Republic of Letters pointed out, forcibly and clearly, that torture could make people confess not only crimes they had not committed, but crimes that no one could commit—a thesis that is anything but quaint or antiquated today. They also became the first to argue in detail that the vast tottering structure of dogma that underpinned the persecution of witches was far too rickety to bear so great a weight. An early citizen of the Republic, Johannes Reuchlin, dared the disapproval of influential men and women across Germany when he wrote a powerful legal defense of the right of Jews to retain their own books, which influential Catholics wanted to burn.[37] Another citizen of the Republic, Sebastian Castellio, first elaborated an even more radical idea, one that flew in the face of religious authority from Saint Augustine on. Once a great admirer of John Calvin’s, Castellio was horrified by Calvin’s part in the arrest and execution of the heretic, Michael Servetus, in 1553. He took action—the sort of action that the citizens of the Republic took. Working with local eminences like Bonifacius Amerbach and Thomas Platter as well as émigrés from Holland and France, all of whom shared his loathing of coercion and violence, Castellio compiled excerpts from early Christian and contemporary works to show that the state had no right to persecute those who did not accept the beliefs of its established church. The Basel printer Joannes Oporinus, whose list included authors of every conceivable ideology and religion, published this work, as subversive in import as it was mild in form, under a false imprint. Each piece of the mosaic Castellio assembled added a new color to his polemical palette. Writing under the pseudonym Martin Bellius, Castellio argued that persecution was literally un-Christian. Those who executed heretics seemed to think that Jesus had been a “Moloch or a god of the sort,” who commanded human sacrifice. Writing as Basilius Montfort, he mounted a more tightly defined political argument. Secular rulers had no right to punish anyone on grounds of belief: “He who suffers persecution on account of his faith stands either in the truth or in error. If he is right he must not be harmed. If he is wrong he must be forgiven. Christ asked God to forgive those who crucified him, for they knew not what they were doing. Would this not apply more greatly to those who allow themselves to be crucified for him?”[38] Castellio’s arguments were hardly rigorous. In the end, he argued, one should judge people by their conduct—a theologically naïve view that could not be reconciled with any Protestant understanding of grace and salvation. His convictions stemmed partly from his wide reading in the early, more radical writings of Martin Luther and the great polemics against persecution by Sebastian Franck, and in part from the lived experience of Basel, where Castellio had seen that men and women of different religions could manage and negotiate their differences—as, some years later, the Hebraist Johannes Buxtorf would manage to publish important editions of Hebrew texts, even though the Jewish printers refused to work on Saturdays, and the Christians on Sunday.

Castellio’s book won few adherents at first. Yet his ideas percolated into the minds of writers like Montaigne and even, so it seems, a few rulers—notably William of Orange and Elizabeth of England.[39] Other citizens of the Republic carried his enterprise onwards, using the literary tools at their disposal since they lacked political ones. The battle against religious prejudice and persecution did not end, of course, in this period, any more than it has ended since. Pierre Bayle—a later citizen of the Republic, a brilliant, bitter critic of absolutism in State and Church who lived in Holland and tormented the authorities with his dazzling pamphlets—shocked many readers when he argued that a society of atheists could live together at peace. And the great philosophes of the eighteenth century—men like Voltaire, who famously left his refuge near Geneva in order to confront the forces of darkness over the Calas case—argued cases like Castellio’s, casting them in a far more radical key. Such characteristic Enlightenment attitudes grew from the speculations of learned men, forced into exile for their beliefs and instructed in the bitter school of political and religious experience that compulsion should never play a role in matters of belief.

Belief in such challenging principles as the free communication of ideas, tolerance in principle if not always in practice, open contact with those of other faiths, and publication of results even when they raised theological difficulties manifested themselves not only in such famous and controversial cases as that of Servetus, but in the everyday life and work of scholars, many of them less courageous—and stiff-necked—than Castellio. And here I pass from cartography to chorography. Like most of those who study the Republic, I have examined only one corner of this vast realm at close range, and in the course of this more limited and detailed scrutiny I have come to see just how the Republicans of Letters used their general canons of conduct to regulate particular, technical forms of inquiry. Starting out in the 1970s, I wanted to understand how men and women could master the whole range of period disciplines and texts, from astronomy to philology; to learn what it felt like to be as skillful at interpreting ancient history as at reading the movements of the planets. So I set out to reconstruct a single discipline that has nowadays largely been forgotten: technical chronology, the formal study of the dates at which events happened in ancient and medieval history. Even in the early modern period, the field was known to be obscure—Johannes Kepler, who knew and loved the subject, noted that books with “Chronology” in their titles didn’t sell.[40]

Still, chronology was a hot field in its day.[41] Leiden University, the most innovative one in Europe, paid the French scholar Joseph Scaliger a higher salary than the law professors and allowed him to forgo lecturing and devote himself to research because of the world-wide reputation he had made as the leading expert on chronology. And it was hard. Chronology demanded, and demands, extraordinary skills: to practice it you had to be able to interpret ancient texts, decipher ancient inscriptions, and even to plot the dates of the eclipses and other astronomical events mentioned in ancient texts, which provide the only absolute dates we have. Chronology posed problems that remain extremely difficult, and to some extent unsolved: for example, how to reconcile the dynasty lists and dates of the Old and New Testaments with one another and with those preserved in secular texts. Its practitioners, accordingly, had to walk fine lines. They could not, in theory, force or falsify any of the evidence. But as soon as they chose one biblical datum to rely on, they laid themselves open to the charge of neglecting others that contradicted it.

A great many early modern scholars wielded this rather scary palette of technical skills with ease and dexterity. Scaliger and his Jesuit critic Denis Petau were probably the best known experts in the field. But chronology also fascinated great astronomers like Copernicus and Kepler, the important composer and musical theorist Seth Calvisius, the erudite Anglican churchman James Ussher, and the most original historical thinker of the whole pre-modern period, Giambattista Vico. These men did extraordinary, wrenchingly difficult work, with meticulous care. By 1700 they had crafted the basic armature of dates on which modern scholars still hang the flesh and blood of ancient and medieval history. Yet they had also begun to study data from other cultures, such as the dynasty lists of the Chinese, that called their basic assumptions into question, and in the end they could not save their beautiful theories from the impact of these obdurate facts.[42]

Scaliger and Kepler, Calvisius and Petau turned out to be as phenomenally learned and analytical, as wide-ranging in their interests and as precise and prophetic in their results as I had believed before I ventured into the labyrinths of their books and manuscripts. But these toiling giants had many human failings. They misreported one another’s ideas; they failed to give credit where credit was clearly due; they ripped one another’s work apart with a zeal that would have been far better spent on other objects.

Academic gossip described chronology as rife with extravagant and willful hypotheses: chronologers, like clocks, never agreed. And some chronologers lived up to these clichés. The erudite Jesuit numismatist and textual critic Jean Hardouin, for example, decided after decades of chronological and philological study that pretty much all the Greek and Latin classics—except for Pliny’s Natural History, which he had edited, and a few other texts—had been forged in the thirteenth century by an “atheistic sect” led by Frederick II of Hohenstaufen. He drew these conclusions partly from an exhaustive study of ancient coins, partly from the texts, which he subjected to the kind of endlessly skeptical scrutiny that adherents of the Baconian theory inflict on the text of Shakespeare. Protestants and Catholics alike were shocked by his radicalism, which provoked bitter debates and unsettled all practitioners of chronology, and all too many of them responded by making the Jesuit order as a whole collectively guilty for Hardouin’s individual fancies.[43] More important—and more generally—it became clear that chronologers, like so many other Republicans of letters, were hypersensitive to slights. Any letter that showed insufficient respect, any publication of a fact or utterance of a word that might reflect badly on them, and they turned on discussion partners and rent them—even when, as Kepler haplessly tried to convince Seth Calvisius, the offended party had simply misunderstood the offender’s use of German.

Yet even as I realized that my chronologers were not such consistent models of scholarly and human virtue as I had hoped, I also found them working hard and effectively to raise bridges across the most profound ideological and theological gaps. Scaliger—a fierce Calvinist who believed, as many of his co-religionists did, that the Pope was the Antichrist—told his students to view the great Catholic church history by Cardinal Baronio with respect. “Every history is good,” he explained: all information mattered, and you could learn far more from a great scholar whose opinions you didn’t share than from a charlatan with whom you went to church.[44]

Chronology could be brutally polemical, but it could also provide an ideal public stage for demonstrations of tolerance, since the chronologer was constantly required to negotiate agreement between sources of radically different origin and nature—a delicate operation at best, and sometimes impossible. To study the Christian past you had to understand the Jewish calendar: not just the sequence of years and months, moreover, but also the nature of religious holidays and observances. Scaliger and his close friend, Isaac Casaubon, realized in the last decades of the sixteenth century that they could not reconstruct the sequence of events or understand the meaning of individual episodes in the Gospels themselves without mastering Jewish scholarship. The Last Supper—as Scaliger pointed out in his first chronology, to the astonishment of erudite theologians—was an adaptation of the Jewish Passover Seder. To understand this primal Christian event, one must read a Passover Haggadah.[45]

But the Haggadah did not clear up all the problems—for example, that of how Jesus had apparently been condemned and executed on days when Jews were prohibited from appearing in court. How were Christians to gain this esoteric knowledge? Scaliger and Casaubon were masters of language, steeped in the Bible. Learning to read Hebrew, in the first instance, had only required them to work out which words were which in the Hebrew version of Genesis, since they already knew it by heart in Latin and French. But the Bible offered nowhere near all the information they needed. To understand exactly the world in which Jesus preached, they had to explore the entire enchanted castle of Jewish learning—chronicles, rabbinical commentaries, even the Talmud. And for guidance through these labyrinths they turned to Jews. Scaliger worked for six months with a very learned convert, Philippus Ferdinandus, who helped him to see that many of Jesus’ precepts, in the Gospels, did not contradict, but actually reflected, Jewish moral teachings. Casaubon invited a learned Jew from Italy, Jacob Barnet, to stay with him for a month at his lodgings at Drury Lane in London. At every meal—one would love to know what they ate—the two men eagerly discussed Jewish texts—including, evidently, the legal ones that Casaubon could not read on his own. Barnet showed Casaubon discussions of Jewish burial practice—which made clear, to the brilliant Calvinist, that Jesus had been buried in a normal, Jewish fashion, rather than, as Cardinal Baronio maintained, in a new way that became the basis of Catholic burial practice.[46]

Neither Scaliger nor Casaubon was especially philo-Semitic in everyday life. But the ethics of scholarship as they understood it brought them into intimate contact with Europe’s local Others. And the contact had a tremendous effect on both of them. Scaliger, the most arrogant scholar in an age when scholarly arrogance flourished, admitted after Ferdinandus died that no Christian could hope to understand the Talmud and other Jewish texts as his friend had. He wept, in a very human way, for his human and intellectual loss. Jacob Barnet, whom the Oxford authorities had destined for public conversion in Saint Mary’s Church, rebelled, ran away, and wound up confined, in miserable conditions, in the university jail, Bocardo. Casaubon—a mild man, bent with age and unremitting study—intervened. He denounced Barnet’s treatment as a violation of Christian ethics; in fact, he went so far as to appeal to King James I—himself an erudite man—on Barnet’s behalf, and his pleas succeeded. A king’s man brought a warrant to Oxford, removed Barnet from prison and put him on the next ship to France. He soon turned up again, man of parts that he was, as an expert on Jewish matters at the French royal court, where he and Giulio Cesare Vanini enjoyed passing gossip about the stinginess of British patrons. The openness that men like Scaliger and Casaubon showed to others whose faith and culture they definitely did not share offered them no practical advantages and could have caused them endless difficulties. It is a tribute to the regulative principles of the Republic—and a sign of their historic impact—that these men behaved as they did.

Both Casaubon and Scaliger, in the course of their work, took on board ideas and ways of doing things that would have shocked—that did shock—some of their contemporaries. Neither went so far as those seventeenth-century Amsterdam Jews who appalled their co-religionists by adopting a form of Karaism—one based not on contact with actual Karaites, but on the descriptions given by Christian Hebraists.[47] Still, Casaubon, after his years of biblical study and his intensive work with Barnet, sometimes even prayed in Hebrew. Scaliger, after even longer years of historical study, made a chronological discovery so profound that even his brilliance could not cope with it: the Egyptian dynasty list of Manetho, according to which history had begun not only before the Flood, but before the Creation. Both men made clear that Christianity represented, in many ways, less a break with the Judaism of the time of Jesus than a new development within it. Historical research was supposed to rear and trim neat, tidy structures, which showed the hand of providence, working to bring Christianity into being. Instead, Scaliger’s and Casaubon’s dangerous ideas and destructive practices undermined the authorities they were expected to support. Yet both men published what they learned—and by doing so disturbed and irritated more orthodox thinkers across the whole European world.

Finally, chronology has a chronology of its own—one that helps us to understand the larger chronology of the Republic of Letters. In the late 1650s, Isaac Vossius—whose father Gerardus had brought him up within the formidable learned tradition of Dutch humanism—shocked the world of learning. He helped to arrange the reprinting in Amsterdam of the Jesuit Martino Martini’s history of China, which set the beginning of the Middle Kingdom so early that only the Greek Old Testament, with its longer chronology, could fit it in after the Flood. And then he published a pamphlet, first in Latin and then in Dutch, in which he insisted that the longer chronology of the Greek Bible, rather than the shorter one of the Hebrew, deserved credence. In doing this Vossius—as should by now be clear—did not forge a new thesis. Ever since Scaliger, chronologers had weighed the difficulties of early history and the virtues of the different biblical versions, and admitted the impossibility of arriving at firm results—in the privacy of their letters and conversations or in the relative privacy of vast Latin treatises. But Vossius—to borrow a term from my late friend and colleague Gerald Geison—turned what had been private science into public science—so public that it provoked a series of pamphlet-sized refutations, which did nothing to soothe the scholarly waters.[48]

A few years later he would literally make the private public by printing Joseph Scaliger’s table talk—which showed that in his chimney corner, talking to his students in a pithy mixture of Latin and French, Scaliger had entertained similarly bold ideas about the duration of history and the incompleteness of the Hebrew Bible.[49]

In these middle years of the seventeenth century, fissures and cracks opened up in many of the fields that mattered to the Republicans. Science and scholarship underwent dramatic transformations in key and tone, as great treatises in Latin gave way to pamphlets in the vernacular, and detailed arguments in dark libraries to lively debates in public venues—and as what had been the practices of erudition revealed what could be a powerful potential to call ancient authorities into question. Traditional histories of the Enlightenment, often centered on France, have tended to treat the eighteenth century in almost Hegelian terms—as the time when the world spirit turned from erudition to philosophy, and scholars became marginal figures in the world of learning.[50] In chronology—as in other fields—older traditions of exegesis and newer methods of historical scholarship, both designed to clarify and confirm traditional structures, ended by destroying them.[51]

The citizens of the early modern Republic of Letters created a virtual community not of those who shared beliefs, but of those who differed. They made up rules for civility: rules that could be used to judge the conduct of all those who offered their intellectual wares for sale in the new, largely free market. They developed new tolerances, for thinkers who disagreed with them on fundamental matters and for facts that challenged their most basic verities. What unified these efforts was a shared, if inchoate and incomplete, respect for truth, for civility, and for the integrity of the human being—a respect not founded, perhaps, on deep philosophical or theological arguments, and often violated in practice, but solid enough to make them bold when they confronted what they saw as superstitions. One of the most prominent citizens of the Republic, Jean Le Clerc—a Swiss, born in Geneva, who moved to Amsterdam to enjoy intellectual freedom—put it well: “If a thing is bad in itself, the example of the ancients does not make it better. Nothing should stop us from improving on them. The Republic of Letters has finally become a land of reason and light, and not of authority and blind faith, as it was for too long. Nowadays numbers prove nothing, and there are no more cabals.”[52] True, in this case Le Clerc was defending not freedom of speech or religion but the use of footnotes in historical texts: but he and his contemporaries wrote with equal clarity and power about religious and political oppression.

Naturally, practices were always more complex—and sometimes much darker and more oppressive—than precepts. Citizens of the Republic of Letters who violated its rules, like Vossius, could change them—but only at the cost of suffering abuse and exclusion. The same fate awaited those who parodied its customs too radically—for example, those who devised erotic readings of the story of the Fall, and took the eating of the apple as an allegory for sexual intercourse. These rash young man found themselves, as Kristine Haugen and Martin Mulsow have shown, deprived of their jobs, hunted from their homes, and forced into poverty and obscurity, by the very fellow scholars who would have defended them if they had not breached the Republic’s codes of decorum.[53] Senior academics, then as now, often showed less tolerance for their junior colleagues than for almost anyone else.

Still, the Republic of Letters provided a stage where free exchange of opinions could sometimes be proclaimed and performed in a new way. Though its story has often been treated as coextensive with that of the eighteenth-century Enlightenment, such accounts foreshorten the traditions of scholarship, debate and sociability that connect the humanist sodalities of Renaissance Florence and Rome to the academies, public libraries, Masonic lodges and salons of the seventeenth and eighteenth centuries. This complex and inspiring history remains to be written.